CA1281411C - Economical high-definition television using a modulated-signal combination - Google Patents
Economical high-definition television using a modulated-signal combinationInfo
- Publication number
- CA1281411C CA1281411C CA000498384A CA498384A CA1281411C CA 1281411 C CA1281411 C CA 1281411C CA 000498384 A CA000498384 A CA 000498384A CA 498384 A CA498384 A CA 498384A CA 1281411 C CA1281411 C CA 1281411C
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- 230000005540 biological transmission Effects 0.000 claims abstract description 32
- 238000001914 filtration Methods 0.000 claims abstract description 17
- 238000007493 shaping process Methods 0.000 claims description 2
- 238000001228 spectrum Methods 0.000 abstract description 28
- 230000000694 effects Effects 0.000 abstract description 6
- 238000010586 diagram Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 3
- 238000013459 approach Methods 0.000 description 2
- USNBCAPIYYPNGO-UHFFFAOYSA-N Decodine Natural products C12=C(O)C(OC)=CC=C2C(N2CCCCC2C2)CC2OC(=O)CCC2=CC=C(O)C1=C2 USNBCAPIYYPNGO-UHFFFAOYSA-N 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- ORQBXQOJMQIAOY-UHFFFAOYSA-N nobelium Chemical compound [No] ORQBXQOJMQIAOY-UHFFFAOYSA-N 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N11/00—Colour television systems
- H04N11/06—Transmission systems characterised by the manner in which the individual colour picture signal components are combined
- H04N11/12—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using simultaneous signals only
- H04N11/14—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using simultaneous signals only in which one signal, modulated in phase and amplitude, conveys colour information and a second signal conveys brightness information, e.g. NTSC-system
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N11/00—Colour television systems
- H04N11/24—High-definition television systems
- H04N11/26—High-definition television systems involving two-channel transmission
Abstract
ECONOMICAL HIGH-DEFINITION TELEVISION USING A MODULATED-SIGNAL COMBINATION
Abstract A television (TV) system having a compatible high-definition signal receivable at conventional resolution by conventional TV receivers without auxiliary apparatus with carrier modulated high-definition luminance information being transmitted in a continuous spectrum spanning two conventional TV channels, carrier modulated quadrature amplitude modulated (QAM) high-frequency chrominance information being transmitted in one TV channel, and carrier modulated QAM low-frequency chrominance information being transmitted in another TV channel. At the transmitter, the high-definition luminance and chrominance signals are first comb filtered to reduce cross-effects between these types of information before modulation. A
decoder recovers the high-definition luminance information by demodulating the transmitted signal and then selectively comb filtering the demodulated luminance information. The chrominance information is recovered from the transmitted signal by first notch filtering the transmitted high-definition signal to remove energy existing between the two sidebands of the QAM high-frequency chrominance information, and then, demodulating at the carrier frequency. The demodulating at the carrier frequency results in the QAM high- and low-frequency chrominance information forming a continuous spectrum that is then bandpass filtered. The high-definition I and Q chrominance signals are then recovered from the bandpass filtered chrominance information by a QAM demodulator. The QAM
demodulation of the latter results in continuous high-definition I and Q chrominance signals. Another embodiment discloses a system having a compatible high-definition signal with carrier modulated high-definition luminance information being transmitted in a continuous spectrum spanning two TV channels including the high-frequency Q
segment of the chrominance information as a single sideband component in one of the TV channels, the high-definition I
chrominance segment and low-frequency Q segment is QAM
coded and frequency translated to the other TV channel before being combined for transmission with the luminance and high-frequency Q segment.
Abstract A television (TV) system having a compatible high-definition signal receivable at conventional resolution by conventional TV receivers without auxiliary apparatus with carrier modulated high-definition luminance information being transmitted in a continuous spectrum spanning two conventional TV channels, carrier modulated quadrature amplitude modulated (QAM) high-frequency chrominance information being transmitted in one TV channel, and carrier modulated QAM low-frequency chrominance information being transmitted in another TV channel. At the transmitter, the high-definition luminance and chrominance signals are first comb filtered to reduce cross-effects between these types of information before modulation. A
decoder recovers the high-definition luminance information by demodulating the transmitted signal and then selectively comb filtering the demodulated luminance information. The chrominance information is recovered from the transmitted signal by first notch filtering the transmitted high-definition signal to remove energy existing between the two sidebands of the QAM high-frequency chrominance information, and then, demodulating at the carrier frequency. The demodulating at the carrier frequency results in the QAM high- and low-frequency chrominance information forming a continuous spectrum that is then bandpass filtered. The high-definition I and Q chrominance signals are then recovered from the bandpass filtered chrominance information by a QAM demodulator. The QAM
demodulation of the latter results in continuous high-definition I and Q chrominance signals. Another embodiment discloses a system having a compatible high-definition signal with carrier modulated high-definition luminance information being transmitted in a continuous spectrum spanning two TV channels including the high-frequency Q
segment of the chrominance information as a single sideband component in one of the TV channels, the high-definition I
chrominance segment and low-frequency Q segment is QAM
coded and frequency translated to the other TV channel before being combined for transmission with the luminance and high-frequency Q segment.
Description
ECONOMICAL HI~H-DEFINITION TELEVISION
USING A MODULATED-SIGNAL COMBINATION
Technical Field This invention relates to a system for improving television (TV) picture quality and particularly to encoding and decoding facilities for use in such a system to provide a high-definition picture to specially designed receivers and usual quality picture to conventional receivers without alterations.
Background of the Invention . _ It has long been desired to provide a high-definition television picture that approaches the ~uality of a projected 35 millimeter photographic film image. See, for example, Image Quality, "~ Comparison of Photographic and Television Systems." Otto H. Schade, Jr.~ RCA
Corporation, 1975.
An approach -to providing high-definition television that could be received as a conventional television picture by conventional television receivers operating according to the National Television Standards Committee (NTSC) re~uirements or could be received as a high-definition television picture by newly designed receivers without requiring prohibitively large bandwidth is disclosed in an article entitled, I'A Compatible High-Definition Television System'9, by T. S. Rzeszewski, The Bell ~ Technical Journal, vol. 62, No. 7, September, 1983, pp. 2091-2111. In that system, the high-frequency luminance and chrominance information and the - 30 conventional luminance and chrominance information are combined into a baseband signal before being modulated by a carrier for the -transmission of the baseband signal on two television channels. This system is particularly applicable to high-power transmitters such as used by commercial television stations since the signal to be transmitt~d is first formed at the baseband level and then modulated and amplified for transmission. Whereas the `` ~Z~l4~L
system proposed by Rzeszewski appears to be applicable for broadcast television, it does have the disadvantage of requiring expensive encoders at the transmitter and expensive decoders in each individual TV receiver.
The article by E. W. ~lerold, entitled, "A
Compatible High-Resolution rrV System for Cablecasting", of the IEEE, VolO 58, No. 7, July, 1970, pp. 1013-1015, suggests that the luminance portion of the TV display can be improved for low-power applications by using an adjacent channel to communicate additional luminance information. ~owever, the latter article does not disclose a method for including the additional luminance infor~ation; nor does it indicate a method for improving the chrominance information9 for reducing cross-effects between the chrominance and luminance information,or for separating the chrominance and luminance in~ormation when modulated and amplified to transmission and power levels.
Therefore, there exists a need for an economical high-definition television system that provides both improved luminance and chrominance information, that reduces cross-effects, and is compatible with NTSC type TV
receivers. Such a system would find wide-spread use in low-power applications such as home cable delivery systems or intercampus video networks such as those proposed for large university campuses or corporation head~uarters.
The foregoing problems are solved and a technical advance is achieved in accordance with the principles of this invention incorporated in a structural embodiment in which high-definition television picture signals are provided that can be received on conventional television sets and that can be received on modified receivers wi-th improved picture quality. Advantageously, high-definition chrominance components are each separately comb filtered to help reduce cross-effects and then modulated and amplified to broadcast power and carrier frequency and, then, combined with a similar modulated and amplified high-definition luminance signal for providing a broadcast signal. The broadcas-t signal is decoded by a decoder that i5 responsive to the latter to demodulate this signal to obtain the luminance signal and chrominance information.
Advantageously, the chrominance components are each band-split into high- and low~frequency segments before modulation. Then, the low-frequency segments are quadrature amplitude modulated (QAM) beEore being modulated at the carrier frequency, and the high-frequency segments are also QAM modulated before being modulated at the carrier frequency. The decoder recovers the chrominance components by notch filtering the carrier modulated high-definition television signal to eliminate spectrum energy between the two sidebands of QAM high-frequency segment and, then, demoduates and bandpass filters the QAM
segments. A single QAM demodulator is then used to recover both high-definition chrominance components from the demodulated and bandpass filtered QAM segments for display - 20 along with the high-definition luminance information.
Advantageously. in another illustrative embodiment of the invention, the high-frequency segment of one chrominance component is first single sideband modulated and summed with the luminance information, and the result is carrier frequency modulated. The other chrominance component and the low-frequency segment of the one chrominance component are QAM modulated with the result being frequency translated to the carrier frequency. The summed and translated information is then combined for transmission.
Advantageously, a decoder is responsive to the transmitted signal to demodulate the luminance information and high-frequency segment of one chrominance component and to demodulate the other chrominance component and the low-frequency segment of the one chrominance component. Thehigh- and low-frequency segments of the one chrominance :
"` ~28~4~
component are then combined in the decoder before being displayed along with the luminance information and other chrominance component.
:~n accordance with one aspect of the invention there is provided a system for encoding high-definition luminance and chrominance information from a high-definition video source for transmission on a transmission media and said high-definition chrominance information having low-frequency and high-frequency chrominance components, said system comprises:
means for modulating said high-definition luminance information at a transmission carrier frequency; means for band splitting said high-definition chrominance information into said low-frequency and high-frequency chrominance components; means for modulating said low-frequency chrominance components at said transmission carrier frequency and at a subcarrier frequency; means for modulating said high-frequency chrominance components at said transmission carrier frequency and at said subcarrier frequency; and means for combining the carrier frequency modulated high-definition luminance information and carrier frequency modulated low-frequency chrominance components and carrier frequency modulated high-frequency chrominance components for transmission on said transmission media.
In accordance with another aspect of the invention ` 25 there is provided a system for decoding high-definition display information from a received hiyh-definition video signal having carrier modulated high-definition luminance and carrier modulated and subcarrier modulated low-frequency and high-frequency chrominance information, said system comprises:
means for demodulating said modulated luminance information in response to the latter and a signal at the carrier frequency for display purposes; and means for demodulating said modulated low-frequency and high-frequency chrominance information in response to the latter and the carrier frequency signal for display purposes.
~ ~.2~
- 4a -~rief Descript_on of the Drawing .
In ~eneral, systern elements, when first introduced in a figure, are each designated with a number that uses the figure number as the most significant digits of the element number.
FIG. 1 is a block diagram of the high-definition encoder of one illustrative embodiment of our invention;
FIG. 2 illustrates the frequency spectrum of the output of the encoder illustrated in FIG. 1.
FIG. 3 is a block diagram of a high-definition decoder of one illustrative embodiment oE our invention for decoding the signal illustrated in FIG. 1 for display purposes;
FIG. 4 illustrates in block diagram form, a high-definition encoder of a second illustrative embodiment ofour invention;
FIG. 5 illustrates the frequency spectrum of the transmitted signal from the encoder of FIG. 4- and FIG. 6 illustrates a block diagram of a high-definition decoder for decodin~ the signal illustrated inFIG. 5 for display purposes.
Detailed Description .
The following describes a television system that is compatible with conventional NTSC receivers and also capable ~f displaying high-resolution television pictures on this system's specially designed receivers. An encoding system for producing the high-definition television signal is illustrated in FIG. 1. Processed video source 112 produces Y, I, and Q signals that have a bandwidth of 7.25 megahertz (~Hz). These Y, I, and Q signals have already been line decimated to 525 lines per frame with a scan rate of the NTSC standard 15.7 kilohertz (kHz). The enooder is re~pon~ive to th6 luminance ~i~n~l at the carrier Erequency, fp. The encoder is responsive to the two color components, I and Q, to comb filter these components to prevent cross-luminance efEects and, then, to separate these two signals into high- and low-frequency I
and Q signals. The low-frequency chrominance ~ignals are then ~uadrature amplitude modulated (QAM) at the color subcarrier, fsc~ before being modulated and amplified at the carrier (or intermediate) frequency, fp. The resulting modulated and amplified signal is then filtered to remove the lower sideband. The high-frequency chrominance signals are also quadrature amplitude modulated at the fsc frequency before being modulated and amplified at the fp frequency. The latter resulting signal is then filtered to remove the upper sideband. All of the modulated and amplified signals are then combined with the frequency modulated (F~) sound to produce the spectrum illustrated in FIG. 2. The luminance information is contained within the spectrum portion 201, the high-frequency chrominance infor~ation is contained within the spectrum portions 202 and 203 with the low-frequency chrominance information being contained within spectrum portion 20~.
Consider now, the operation in the encoder illustrated in FIGo 1 in greater detail. The luminance signal from processed video source 112 is first comb filtered by filter 115 to remove any energy at or near odd multiples of half the horizontal line rate (fh). After being comb filtered, the Y signal is power modulated by modulator 10~. The output of modulator 10g is then filtered by vestigial sideband filter 110 to remove any undesired frequencies resulting from the modulation by element 109 that might interfere with other portions of the spectrum illustrated in FIG. 2 and a portion of the upper sideband above fp ~ 3 M~Iz. The output of filter 110 is represented in FIG. 2 by spectrum portion 201~
Consider now, how the encoder illustrated in FIG. 1 encodes the I and Q signals from processed video source 112. The I and Q signals are first comb filtered by ~.Z8~
ilters 113 and 114, respectively, to prevent cross-effects when the signals are eventually interleaved in summer 111.
The resulting signals from filters 113 and 119 are then separated into low- and high-frequency portions by band splitters 101 and 105. QAM encoder 102 is responsive to the low-frequency portion of the I and Q signals to quadrature modulate these signals at the fsc frequency in a manner similar to an NTSC color encoder but with the bandwidth being limited to 0.5 MHz. The output of element 102 is then modulated and amplified at the carrier frequency by modulator 103. The output of modulator 103 is then filtered to remove the lower sideband resulting in the spectrum portion 204 of FIG. 2~ The high-frequency portion of the I and Q signals are similarly encoded by encoder 15 106, modulated and ampliEied by element 107, and the upper sideband removed by filter 103 resulting in spectrum portions 202 and 203. The outputs of filters 104, 108 and 110 and FM modulator 115 are then combined by summer 111 for transmission over the broadcast medium.
FIG. 3 illustrates a decoder for receiving the transmitted output of the encoder of FIG. 1 for display purposes. The luminance information is recovered from the transmitted signal by filter 301 performing a vestigial sideband shaping of the transmitted signal and removing the low-frequency chrominance before the signal is demodulated with a signal at the carrier ~requency r fp, by demodulator 302. Low~pass filter 303 then rejects all frequencies above 7.25, and Eilter 304 comb filters the output of filter 303 so as to remove any interfering high-frequency chrominance components. The resulting Y signalis then available for display purposes.
~ he total chrominance signal (I and Q) is recovered ~rom the transmitted signal by notch filter 305 filtering out the frequencies illustratively between fP ~ fsc + 0 5 MHz which is the spectral region between spectrum portions 202 and 203. The output of filter 305 is then demodulated by demodulator 306. The _`7 _ output of demodulator 306 is then bandpass filtered by filter 307 to eliminate frequencies except those between 1.6 and 5.6 MHz. The output of filter 307 is then QAM
demodulated by element 308 with a signal at the color subcarrier frequency, fs~, to recover the chrominance signals. The resulting chrominance signals from demodulator 308 are then comb filtered over a fre~uency range of 0.5 to 2.0 MHz to remove any interference between the high-frequency chrominance signal and the luminance signal.
The resulting I and Q signals comb filters 309 and 310/ respectively, as well as the resulting Y signal from comb Eilter 304 are then available for display by a high-definition display monitor.
Another illustrative embodiment of an encoder, in accordance with our invention, is illustrated in FIG. 4.
The frequency spectrum generated by the encoder of FIG. 4 is illustrated in FIG. 5, and the output of the encoder of FIG. 4 is directly communicated on the broadcast media.
The chrominance signals, I and QL, are encoded into spectrum portions 502 and 5U3 of FIG. 5 in the manner described below. The high-Erequency Q signal is encoded into spectrum portion 504. The requency spectrum of I is matched to that of the high- and low-frequency Q signals, 25 QH and QL, respectively. First, the I and Q signals from processed video source 401 are comb filtered by filters 402 and 404, respectively, to prevent cross-effects and then low-pass filtered in the appropriate manner by filters 403 and 405 to properly band limit these signals.
The outputs of filters 403 and 405 are then encoded by encoder 406 in the normal NTSC color coding manner. The output of encoder 406 is then filtered to eliminate the vestigial sidebands of the modulated I signal by filter 407. The output of filter 407 is then frequency translated and amplified so as to occupy spectrum portions 502 and 503 in FIG. 5.
The high-frequency chrominance portion of the Q
i~28~
signal, QH, which is indicated by spectrum portion 50~
of FIG. 5, is formed in the following manner. The Q signal from processed video source 401 is first comb filtered by filter ~09 to eliminate any vertical spectrum near odd multiples of half the line rate (fh) then bandpass filtered by filter 410 to allow only the fre~uencies between 0.5 to 1.5 MH~ to be used. The output of filter 410 is then single sideband modulated at a frequency which may advantageously be 1.5 times fsc by modulator 411.
The output of modulator 411 is combined by summer A12 with the luminance information, Y, from processed video source 401 which has been low-pass filtered to limit the Y signal to a range of 0 to 7.25 MHz after having first been comb filtered by filter 418 to remove any energy in the vertical spectrum near odd multiples of fh/2. The output of summer 412 is then double sideband modulated by modulator ; 414 and vestigal sideband filtered by filter 415 to remove components above fc ~ 4.2 MHz. Summer 417 then forms the signal to be transmitted on the transmission media by combining the outputs of the sound ~M modulator 416, frequency translator 408 (consisting of a modulator with a carrier frequency fc and an upper sideband filter to remove the lower sideband) and filter 415 to produce the spectrum illustrated in FIG. 5.
~ 25 A decoder illustrated in FIG. 6 is an illustrative `~ embodiment of a decoder for decoding the signal illustrated in FIG . 5 . Tuner 601 is responsive to the signal illustrated in FIG. 5 to communicate this signal to IF
stages 602 and 607. IF stage 602 is similar to the 30 standard NTSC IF stage. The sound is captured from the signal by sound detector 612 which is similar to a standard NTSC sound detector. The low-frequency chrominance signals that are contained in spectrum portions S0~ and 503 of FIG. 5 are detected by detector ~03 in a manner similar to 35 the standard NTSC method. The I signal from detector 603 is then comb filtered by filter 606 to eliminate any 9 interference from the luminance signal. The low-frequency ,~
~1.28~
g signal, QL' from detector 603 is then combined with the high-frequency signal. QH ? by summer 604 and then comb filtered by filter 605 to eliminate any interference from the luminance signal.
S The luminance signal, Y, and the high-frequency signal, QH, are detected in the following manner. IF
stage 607 is responsive to the output of tuner 601 to extract the information contained in the spectrum of FIG. 5 from approximately -7.25 MH~ to 1.25 M~z with respect to the carrier frequency fc~ Detector 608 then frequency translates and limits this information so as to reproduce a portion of spectrum portion 501 and spectrum 504. Comb filter 611 then filters the output of detector 608 to eliminate the high-fre~uency chrominance signal, QH~ from Y, which is in the region between 6 to 7 MHz.
The high-frequency chrominance component, Q~l' is demodulated by single sideband demodulator 609. The QH
signal is then combined with the QL signal by summer 604 as previously described. The outputs of filters 606, 605, and 611 are then displayed on a high-definition monitor display.
It is to be understood that the above-described embodiment is merely ilustrative of the principles of the invention and that other arrangements may be devised by those skilled in the art without departing from the spirit and scope of the invention.
.
"
USING A MODULATED-SIGNAL COMBINATION
Technical Field This invention relates to a system for improving television (TV) picture quality and particularly to encoding and decoding facilities for use in such a system to provide a high-definition picture to specially designed receivers and usual quality picture to conventional receivers without alterations.
Background of the Invention . _ It has long been desired to provide a high-definition television picture that approaches the ~uality of a projected 35 millimeter photographic film image. See, for example, Image Quality, "~ Comparison of Photographic and Television Systems." Otto H. Schade, Jr.~ RCA
Corporation, 1975.
An approach -to providing high-definition television that could be received as a conventional television picture by conventional television receivers operating according to the National Television Standards Committee (NTSC) re~uirements or could be received as a high-definition television picture by newly designed receivers without requiring prohibitively large bandwidth is disclosed in an article entitled, I'A Compatible High-Definition Television System'9, by T. S. Rzeszewski, The Bell ~ Technical Journal, vol. 62, No. 7, September, 1983, pp. 2091-2111. In that system, the high-frequency luminance and chrominance information and the - 30 conventional luminance and chrominance information are combined into a baseband signal before being modulated by a carrier for the -transmission of the baseband signal on two television channels. This system is particularly applicable to high-power transmitters such as used by commercial television stations since the signal to be transmitt~d is first formed at the baseband level and then modulated and amplified for transmission. Whereas the `` ~Z~l4~L
system proposed by Rzeszewski appears to be applicable for broadcast television, it does have the disadvantage of requiring expensive encoders at the transmitter and expensive decoders in each individual TV receiver.
The article by E. W. ~lerold, entitled, "A
Compatible High-Resolution rrV System for Cablecasting", of the IEEE, VolO 58, No. 7, July, 1970, pp. 1013-1015, suggests that the luminance portion of the TV display can be improved for low-power applications by using an adjacent channel to communicate additional luminance information. ~owever, the latter article does not disclose a method for including the additional luminance infor~ation; nor does it indicate a method for improving the chrominance information9 for reducing cross-effects between the chrominance and luminance information,or for separating the chrominance and luminance in~ormation when modulated and amplified to transmission and power levels.
Therefore, there exists a need for an economical high-definition television system that provides both improved luminance and chrominance information, that reduces cross-effects, and is compatible with NTSC type TV
receivers. Such a system would find wide-spread use in low-power applications such as home cable delivery systems or intercampus video networks such as those proposed for large university campuses or corporation head~uarters.
The foregoing problems are solved and a technical advance is achieved in accordance with the principles of this invention incorporated in a structural embodiment in which high-definition television picture signals are provided that can be received on conventional television sets and that can be received on modified receivers wi-th improved picture quality. Advantageously, high-definition chrominance components are each separately comb filtered to help reduce cross-effects and then modulated and amplified to broadcast power and carrier frequency and, then, combined with a similar modulated and amplified high-definition luminance signal for providing a broadcast signal. The broadcas-t signal is decoded by a decoder that i5 responsive to the latter to demodulate this signal to obtain the luminance signal and chrominance information.
Advantageously, the chrominance components are each band-split into high- and low~frequency segments before modulation. Then, the low-frequency segments are quadrature amplitude modulated (QAM) beEore being modulated at the carrier frequency, and the high-frequency segments are also QAM modulated before being modulated at the carrier frequency. The decoder recovers the chrominance components by notch filtering the carrier modulated high-definition television signal to eliminate spectrum energy between the two sidebands of QAM high-frequency segment and, then, demoduates and bandpass filters the QAM
segments. A single QAM demodulator is then used to recover both high-definition chrominance components from the demodulated and bandpass filtered QAM segments for display - 20 along with the high-definition luminance information.
Advantageously. in another illustrative embodiment of the invention, the high-frequency segment of one chrominance component is first single sideband modulated and summed with the luminance information, and the result is carrier frequency modulated. The other chrominance component and the low-frequency segment of the one chrominance component are QAM modulated with the result being frequency translated to the carrier frequency. The summed and translated information is then combined for transmission.
Advantageously, a decoder is responsive to the transmitted signal to demodulate the luminance information and high-frequency segment of one chrominance component and to demodulate the other chrominance component and the low-frequency segment of the one chrominance component. Thehigh- and low-frequency segments of the one chrominance :
"` ~28~4~
component are then combined in the decoder before being displayed along with the luminance information and other chrominance component.
:~n accordance with one aspect of the invention there is provided a system for encoding high-definition luminance and chrominance information from a high-definition video source for transmission on a transmission media and said high-definition chrominance information having low-frequency and high-frequency chrominance components, said system comprises:
means for modulating said high-definition luminance information at a transmission carrier frequency; means for band splitting said high-definition chrominance information into said low-frequency and high-frequency chrominance components; means for modulating said low-frequency chrominance components at said transmission carrier frequency and at a subcarrier frequency; means for modulating said high-frequency chrominance components at said transmission carrier frequency and at said subcarrier frequency; and means for combining the carrier frequency modulated high-definition luminance information and carrier frequency modulated low-frequency chrominance components and carrier frequency modulated high-frequency chrominance components for transmission on said transmission media.
In accordance with another aspect of the invention ` 25 there is provided a system for decoding high-definition display information from a received hiyh-definition video signal having carrier modulated high-definition luminance and carrier modulated and subcarrier modulated low-frequency and high-frequency chrominance information, said system comprises:
means for demodulating said modulated luminance information in response to the latter and a signal at the carrier frequency for display purposes; and means for demodulating said modulated low-frequency and high-frequency chrominance information in response to the latter and the carrier frequency signal for display purposes.
~ ~.2~
- 4a -~rief Descript_on of the Drawing .
In ~eneral, systern elements, when first introduced in a figure, are each designated with a number that uses the figure number as the most significant digits of the element number.
FIG. 1 is a block diagram of the high-definition encoder of one illustrative embodiment of our invention;
FIG. 2 illustrates the frequency spectrum of the output of the encoder illustrated in FIG. 1.
FIG. 3 is a block diagram of a high-definition decoder of one illustrative embodiment oE our invention for decoding the signal illustrated in FIG. 1 for display purposes;
FIG. 4 illustrates in block diagram form, a high-definition encoder of a second illustrative embodiment ofour invention;
FIG. 5 illustrates the frequency spectrum of the transmitted signal from the encoder of FIG. 4- and FIG. 6 illustrates a block diagram of a high-definition decoder for decodin~ the signal illustrated inFIG. 5 for display purposes.
Detailed Description .
The following describes a television system that is compatible with conventional NTSC receivers and also capable ~f displaying high-resolution television pictures on this system's specially designed receivers. An encoding system for producing the high-definition television signal is illustrated in FIG. 1. Processed video source 112 produces Y, I, and Q signals that have a bandwidth of 7.25 megahertz (~Hz). These Y, I, and Q signals have already been line decimated to 525 lines per frame with a scan rate of the NTSC standard 15.7 kilohertz (kHz). The enooder is re~pon~ive to th6 luminance ~i~n~l at the carrier Erequency, fp. The encoder is responsive to the two color components, I and Q, to comb filter these components to prevent cross-luminance efEects and, then, to separate these two signals into high- and low-frequency I
and Q signals. The low-frequency chrominance ~ignals are then ~uadrature amplitude modulated (QAM) at the color subcarrier, fsc~ before being modulated and amplified at the carrier (or intermediate) frequency, fp. The resulting modulated and amplified signal is then filtered to remove the lower sideband. The high-frequency chrominance signals are also quadrature amplitude modulated at the fsc frequency before being modulated and amplified at the fp frequency. The latter resulting signal is then filtered to remove the upper sideband. All of the modulated and amplified signals are then combined with the frequency modulated (F~) sound to produce the spectrum illustrated in FIG. 2. The luminance information is contained within the spectrum portion 201, the high-frequency chrominance infor~ation is contained within the spectrum portions 202 and 203 with the low-frequency chrominance information being contained within spectrum portion 20~.
Consider now, the operation in the encoder illustrated in FIGo 1 in greater detail. The luminance signal from processed video source 112 is first comb filtered by filter 115 to remove any energy at or near odd multiples of half the horizontal line rate (fh). After being comb filtered, the Y signal is power modulated by modulator 10~. The output of modulator 10g is then filtered by vestigial sideband filter 110 to remove any undesired frequencies resulting from the modulation by element 109 that might interfere with other portions of the spectrum illustrated in FIG. 2 and a portion of the upper sideband above fp ~ 3 M~Iz. The output of filter 110 is represented in FIG. 2 by spectrum portion 201~
Consider now, how the encoder illustrated in FIG. 1 encodes the I and Q signals from processed video source 112. The I and Q signals are first comb filtered by ~.Z8~
ilters 113 and 114, respectively, to prevent cross-effects when the signals are eventually interleaved in summer 111.
The resulting signals from filters 113 and 119 are then separated into low- and high-frequency portions by band splitters 101 and 105. QAM encoder 102 is responsive to the low-frequency portion of the I and Q signals to quadrature modulate these signals at the fsc frequency in a manner similar to an NTSC color encoder but with the bandwidth being limited to 0.5 MHz. The output of element 102 is then modulated and amplified at the carrier frequency by modulator 103. The output of modulator 103 is then filtered to remove the lower sideband resulting in the spectrum portion 204 of FIG. 2~ The high-frequency portion of the I and Q signals are similarly encoded by encoder 15 106, modulated and ampliEied by element 107, and the upper sideband removed by filter 103 resulting in spectrum portions 202 and 203. The outputs of filters 104, 108 and 110 and FM modulator 115 are then combined by summer 111 for transmission over the broadcast medium.
FIG. 3 illustrates a decoder for receiving the transmitted output of the encoder of FIG. 1 for display purposes. The luminance information is recovered from the transmitted signal by filter 301 performing a vestigial sideband shaping of the transmitted signal and removing the low-frequency chrominance before the signal is demodulated with a signal at the carrier ~requency r fp, by demodulator 302. Low~pass filter 303 then rejects all frequencies above 7.25, and Eilter 304 comb filters the output of filter 303 so as to remove any interfering high-frequency chrominance components. The resulting Y signalis then available for display purposes.
~ he total chrominance signal (I and Q) is recovered ~rom the transmitted signal by notch filter 305 filtering out the frequencies illustratively between fP ~ fsc + 0 5 MHz which is the spectral region between spectrum portions 202 and 203. The output of filter 305 is then demodulated by demodulator 306. The _`7 _ output of demodulator 306 is then bandpass filtered by filter 307 to eliminate frequencies except those between 1.6 and 5.6 MHz. The output of filter 307 is then QAM
demodulated by element 308 with a signal at the color subcarrier frequency, fs~, to recover the chrominance signals. The resulting chrominance signals from demodulator 308 are then comb filtered over a fre~uency range of 0.5 to 2.0 MHz to remove any interference between the high-frequency chrominance signal and the luminance signal.
The resulting I and Q signals comb filters 309 and 310/ respectively, as well as the resulting Y signal from comb Eilter 304 are then available for display by a high-definition display monitor.
Another illustrative embodiment of an encoder, in accordance with our invention, is illustrated in FIG. 4.
The frequency spectrum generated by the encoder of FIG. 4 is illustrated in FIG. 5, and the output of the encoder of FIG. 4 is directly communicated on the broadcast media.
The chrominance signals, I and QL, are encoded into spectrum portions 502 and 5U3 of FIG. 5 in the manner described below. The high-Erequency Q signal is encoded into spectrum portion 504. The requency spectrum of I is matched to that of the high- and low-frequency Q signals, 25 QH and QL, respectively. First, the I and Q signals from processed video source 401 are comb filtered by filters 402 and 404, respectively, to prevent cross-effects and then low-pass filtered in the appropriate manner by filters 403 and 405 to properly band limit these signals.
The outputs of filters 403 and 405 are then encoded by encoder 406 in the normal NTSC color coding manner. The output of encoder 406 is then filtered to eliminate the vestigial sidebands of the modulated I signal by filter 407. The output of filter 407 is then frequency translated and amplified so as to occupy spectrum portions 502 and 503 in FIG. 5.
The high-frequency chrominance portion of the Q
i~28~
signal, QH, which is indicated by spectrum portion 50~
of FIG. 5, is formed in the following manner. The Q signal from processed video source 401 is first comb filtered by filter ~09 to eliminate any vertical spectrum near odd multiples of half the line rate (fh) then bandpass filtered by filter 410 to allow only the fre~uencies between 0.5 to 1.5 MH~ to be used. The output of filter 410 is then single sideband modulated at a frequency which may advantageously be 1.5 times fsc by modulator 411.
The output of modulator 411 is combined by summer A12 with the luminance information, Y, from processed video source 401 which has been low-pass filtered to limit the Y signal to a range of 0 to 7.25 MHz after having first been comb filtered by filter 418 to remove any energy in the vertical spectrum near odd multiples of fh/2. The output of summer 412 is then double sideband modulated by modulator ; 414 and vestigal sideband filtered by filter 415 to remove components above fc ~ 4.2 MHz. Summer 417 then forms the signal to be transmitted on the transmission media by combining the outputs of the sound ~M modulator 416, frequency translator 408 (consisting of a modulator with a carrier frequency fc and an upper sideband filter to remove the lower sideband) and filter 415 to produce the spectrum illustrated in FIG. 5.
~ 25 A decoder illustrated in FIG. 6 is an illustrative `~ embodiment of a decoder for decoding the signal illustrated in FIG . 5 . Tuner 601 is responsive to the signal illustrated in FIG. 5 to communicate this signal to IF
stages 602 and 607. IF stage 602 is similar to the 30 standard NTSC IF stage. The sound is captured from the signal by sound detector 612 which is similar to a standard NTSC sound detector. The low-frequency chrominance signals that are contained in spectrum portions S0~ and 503 of FIG. 5 are detected by detector ~03 in a manner similar to 35 the standard NTSC method. The I signal from detector 603 is then comb filtered by filter 606 to eliminate any 9 interference from the luminance signal. The low-frequency ,~
~1.28~
g signal, QL' from detector 603 is then combined with the high-frequency signal. QH ? by summer 604 and then comb filtered by filter 605 to eliminate any interference from the luminance signal.
S The luminance signal, Y, and the high-frequency signal, QH, are detected in the following manner. IF
stage 607 is responsive to the output of tuner 601 to extract the information contained in the spectrum of FIG. 5 from approximately -7.25 MH~ to 1.25 M~z with respect to the carrier frequency fc~ Detector 608 then frequency translates and limits this information so as to reproduce a portion of spectrum portion 501 and spectrum 504. Comb filter 611 then filters the output of detector 608 to eliminate the high-fre~uency chrominance signal, QH~ from Y, which is in the region between 6 to 7 MHz.
The high-frequency chrominance component, Q~l' is demodulated by single sideband demodulator 609. The QH
signal is then combined with the QL signal by summer 604 as previously described. The outputs of filters 606, 605, and 611 are then displayed on a high-definition monitor display.
It is to be understood that the above-described embodiment is merely ilustrative of the principles of the invention and that other arrangements may be devised by those skilled in the art without departing from the spirit and scope of the invention.
.
"
Claims (14)
1. A system for encoding high-definition luminance and chrominance information from a high-definition video source for transmission on a transmission media and said high-definition chrominance information having low-frequency and high-frequency chrominance components, said system comprises:
means for modulating said high-definition luminance information at a transmission carrier frequency;
means for band splitting said high-definition chrominance information into said low-frequency and high-frequency chrominance components;
means for modulating said low-frequency chrominance components at said transmission carrier frequency and at a subcarrier frequency;
means for modulating said high-frequency chrominance components at said transmission carrier frequency and at said subcarrier frequency; and means for combining the carrier frequency modulated high-definition luminance information and carrier frequency modulated low-frequency chrominance components and carrier frequency modulated high-frequency chrominance components for transmission on said transmission media.
means for modulating said high-definition luminance information at a transmission carrier frequency;
means for band splitting said high-definition chrominance information into said low-frequency and high-frequency chrominance components;
means for modulating said low-frequency chrominance components at said transmission carrier frequency and at a subcarrier frequency;
means for modulating said high-frequency chrominance components at said transmission carrier frequency and at said subcarrier frequency; and means for combining the carrier frequency modulated high-definition luminance information and carrier frequency modulated low-frequency chrominance components and carrier frequency modulated high-frequency chrominance components for transmission on said transmission media.
2. A system for decoding high-definition display information from a received high-definition video signal having carrier modulated high-definition luminance and carrier modulated and subcarrier modulated low-frequency and high-frequency chrominance information, said system comprises:
means for demodulating said modulated luminance information in response to the latter and a signal at the carrier frequency for display purposes; and means for demodulating said modulated low-frequency and high-frequency chrominance information in response to the latter and the carrier frequency signal for display purposes.
means for demodulating said modulated luminance information in response to the latter and a signal at the carrier frequency for display purposes; and means for demodulating said modulated low-frequency and high-frequency chrominance information in response to the latter and the carrier frequency signal for display purposes.
3. A system for encoding high-definition luminance and chrominance information from a high-definition video source for transmission on a transmission media and said high-definition chrominance information having low-frequency and high-frequency chrominance components, said system comprises:
means for modulating said high-definition luminance information at a transmission carrier frequency;
means for band splitting said high-definition chrominance information into said low-frequency and high-frequency chrominance components;
means for quadrature amplitude modulating said low frequency chrominance components;
means for modulating the quadrature amplitude modulated low-frequency chrominance components at said transmission carrier frequency;
means for quadrature amplitude modulating said high-frequency chrominance components;
means for modulating the quadrature amplitude modulated high-frequency chrominance components at said transmission carrier frequency; and means for combining the carrier frequency modulated high-definition luminance information and low-frequency chrominance component and high-frequency chrominance component for transmission on said transmission media.
means for modulating said high-definition luminance information at a transmission carrier frequency;
means for band splitting said high-definition chrominance information into said low-frequency and high-frequency chrominance components;
means for quadrature amplitude modulating said low frequency chrominance components;
means for modulating the quadrature amplitude modulated low-frequency chrominance components at said transmission carrier frequency;
means for quadrature amplitude modulating said high-frequency chrominance components;
means for modulating the quadrature amplitude modulated high-frequency chrominance components at said transmission carrier frequency; and means for combining the carrier frequency modulated high-definition luminance information and low-frequency chrominance component and high-frequency chrominance component for transmission on said transmission media.
4. The system of claim 3 further comprises means for comb filtering said high-definition luminance information received from said video source before modulation by said luminance modulating means; and means for comb filtering said high-definition chrominance information received from said video source before the latter is band split into said high- and low-frequency chrominance components.
5. The system of claim 4 wherein said luminance modulating means comprises means for vestigially sideband filtering said carrier frequency modulated luminance information before transmission.
6. A system for decoding high-definition luminance and chrominance information from a transmitted signal having carrier modulated high-definition luminance information and carrier modulated quadrature amplitude modulated high-frequency chrominance information and quadrature amplitude modulated low-frequency chrominance information, said system comprises:
means for demodulating said modulated luminance information in response to said transmitted signal and a carrier frequency signal;
means for low-pass filtering said demodulated luminance information;
means for comb filtering said bandpass limited luminance information for display purposes;
means responsive to said carrier modulated quadrature amplitude modulated high-frequency and low-frequency chrominance information for notch filtering the latter information;
means for demodulating said notch filtered high-frequency and low-frequency chrominance information;
means for bandpass filtering said demodulated high-frequency and low-frequency chrominance information; and means for quadrature amplitude demodulating said band limited high frequency and low-frequency chrominance information for display purposes.
means for demodulating said modulated luminance information in response to said transmitted signal and a carrier frequency signal;
means for low-pass filtering said demodulated luminance information;
means for comb filtering said bandpass limited luminance information for display purposes;
means responsive to said carrier modulated quadrature amplitude modulated high-frequency and low-frequency chrominance information for notch filtering the latter information;
means for demodulating said notch filtered high-frequency and low-frequency chrominance information;
means for bandpass filtering said demodulated high-frequency and low-frequency chrominance information; and means for quadrature amplitude demodulating said band limited high frequency and low-frequency chrominance information for display purposes.
7. The system of claim 6 wherein said luminance demodulating means further comprises means for vestigial sideband shaping said carrier modulated high-definition luminance information upon receiving the latter information.
8. The system of claim 7 further comprises means for recovering the carrier frequency from said transmitted signal; and said quadrature amplitude modulated demodulating means further comprises means for comb filtering the demodulated high-frequency and low-frequency chrominance information.
9. A system for encoding high-definition luminance and chrominance information from a high-definition video source for transmission on a transmission media and said video source having first and second chrominance components and said second chrominance component having high- and low-frequency segments, said system comprises:
means for low-pass limiting said high definition luminance information to produce low-pass limited luminance information;
means for band limiting the high-frequency segment of said second chrominance component;
means for single sideband modulating said band limited high-frequency segment of said second chrominance component at a carrier frequency;
means for summing said single sideband modulated high-frequency segment of said second chrominance component and said low-pass limited luminance information;
means for double sideband modulating the summed information;
means responsive to said first chrominance component and said low-frequency segment of said second chrominance component for modulating the latter component and segment;
means responsive to the modulated first chrominance component and low-frequency segment for frequency translating the latter to the carrier frequency; and means responsive to the frequency translated chrominance component and low-frequency segment and the summed information for combining the latter for transmission on said transmission media.
means for low-pass limiting said high definition luminance information to produce low-pass limited luminance information;
means for band limiting the high-frequency segment of said second chrominance component;
means for single sideband modulating said band limited high-frequency segment of said second chrominance component at a carrier frequency;
means for summing said single sideband modulated high-frequency segment of said second chrominance component and said low-pass limited luminance information;
means for double sideband modulating the summed information;
means responsive to said first chrominance component and said low-frequency segment of said second chrominance component for modulating the latter component and segment;
means responsive to the modulated first chrominance component and low-frequency segment for frequency translating the latter to the carrier frequency; and means responsive to the frequency translated chrominance component and low-frequency segment and the summed information for combining the latter for transmission on said transmission media.
10. The system of claim 9 further comprising means for comb filtering said low-frequency and high-frequency segments of said second chrominance component upon reception from said video source.
11. The system of claim 10 wherein said double sideband modulating means comprises means for vestigially sideband filtering said double sideband modulated information.
12. A system for decoding high-definition luminance and chrominance information from a transmitted signal and said high-definition chrominance information comprising a first and second chrominance component and said second chrominance component comprises low- and high-frequency segments, said transmitted signal having carrier modulated high-definition luminance information with said high-frequency segment of said
13 second chrominance component, and said low-frequency segment of said second chrominance component and said first chrominance component modulated and frequency translated to the carrier frequency, said system comprises:
means for detecting said carrier modulated high-definition luminance information with said high-frequency segment;
means responsive to said detected information for comb filtering the latter to obtain said high-definition luminance information for display purposes;
means responsive to said detected information for single sideband demodulating said information to obtain said high-frequency segment of said second chrominance component;
means for demodulating said first chrominance component for display purposes from said transmitted signal;
means for demodulating said low-frequency segment of said second chrominance component; and means responsive to the demodulated low-frequency segment of said second chrominance component and the demodulated high-frequency segment of said second chrominance component for summing the latter for display purposes.
13. The system of claim 12 further comprises means for comb filtering said first chrominance component for display purposes; and said summing means comprises means for comb filtering the summed information for display purposes.
means for detecting said carrier modulated high-definition luminance information with said high-frequency segment;
means responsive to said detected information for comb filtering the latter to obtain said high-definition luminance information for display purposes;
means responsive to said detected information for single sideband demodulating said information to obtain said high-frequency segment of said second chrominance component;
means for demodulating said first chrominance component for display purposes from said transmitted signal;
means for demodulating said low-frequency segment of said second chrominance component; and means responsive to the demodulated low-frequency segment of said second chrominance component and the demodulated high-frequency segment of said second chrominance component for summing the latter for display purposes.
13. The system of claim 12 further comprises means for comb filtering said first chrominance component for display purposes; and said summing means comprises means for comb filtering the summed information for display purposes.
14
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/684,489 US4641179A (en) | 1984-12-21 | 1984-12-21 | Economical high-definition television using a modulated-signal combination |
| US684,489 | 1984-12-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1281411C true CA1281411C (en) | 1991-03-12 |
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ID=24748247
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000498384A Expired - Lifetime CA1281411C (en) | 1984-12-21 | 1985-12-20 | Economical high-definition television using a modulated-signal combination |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4641179A (en) |
| CA (1) | CA1281411C (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4839720A (en) * | 1987-07-27 | 1989-06-13 | General Electric Company | Compatible widescreen television system with auxiliary subcarrier modulated by side panel high frequency information |
| CA1303727C (en) * | 1987-08-28 | 1992-06-16 | Institut National De La Recherche Scientifique | Apparatus and method for encoding and decoding a ntsc color video signal |
| GB8721565D0 (en) * | 1987-09-14 | 1987-10-21 | Rca Corp | Video signal processing system |
| IN170842B (en) * | 1987-09-14 | 1992-05-30 | Gen Electric | |
| DE3732734A1 (en) * | 1987-09-29 | 1989-04-13 | Thomson Brandt Gmbh | VIDEO RECORDER |
| GB8800420D0 (en) * | 1988-01-08 | 1988-02-10 | Rca Corp | Dual single sideband modulator for actv |
| US4967272A (en) * | 1988-01-27 | 1990-10-30 | Communications Satellite Corporation | Bandwidth reduction and multiplexing of multiple component TV signals |
| US4837611A (en) * | 1988-02-03 | 1989-06-06 | Faroudja Y C | Wideband NTSC-compatible transmission system with noise reduction processing |
| US5081521A (en) * | 1990-04-13 | 1992-01-14 | Faroudja Y C | NTSC color television system with improved chroma bandwidth and chroma ringing reduction |
| KR920010784B1 (en) * | 1990-05-11 | 1992-12-17 | 삼성전자 주식회사 | Hdtv signal transmitting method and circuit |
| KR950005068B1 (en) * | 1990-11-05 | 1995-05-17 | 삼성전자주식회사 | Television signal processing methods and apparatus for employing a narrow bandwidth having a color-under spectral format for high quality video recording system |
| US5105442A (en) * | 1990-11-07 | 1992-04-14 | At&T Bell Laboratories | Coded modulation with unequal error protection |
| JP3167745B2 (en) * | 1991-07-17 | 2001-05-21 | 日本放送協会 | Digital modem |
| US5267021A (en) * | 1992-04-03 | 1993-11-30 | The Trustees Of Columbia University In The City Of New York | Multiresolution digital television broadcast system |
| US5398073A (en) * | 1994-04-12 | 1995-03-14 | At&T Corp. | Concatenated coded vestigial sideband modulation for high definition television |
| JPH08163458A (en) * | 1994-11-30 | 1996-06-21 | Sony Corp | Video image detector |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL164804B (en) * | 1950-07-28 | Hoechst Ag | A SUPPORT SUITABLE FOR THE MANUFACTURE OF FLAT PRINTING PLATES AS WELL AS A FLAT PRINTING PLATE CONSISTING OF SUCH A SUPPORT TO WHICH A LIGHT-SENSITIVE LAYER HAS BEEN APPLIED. | |
| GB1582984A (en) * | 1976-08-09 | 1981-01-21 | Rca Corp | Video signal recording systems |
| GB2113941A (en) * | 1982-01-25 | 1983-08-10 | Philips Electronic Associated | Television transmission system |
| US4521803A (en) * | 1982-10-07 | 1985-06-04 | General Electric Company | System for compatible transmission of high-resolution TV |
| US4564857A (en) * | 1984-02-28 | 1986-01-14 | At&T Bell Laboratories | Aspect ratio improvement for compatible high-definition television |
-
1984
- 1984-12-21 US US06/684,489 patent/US4641179A/en not_active Expired - Lifetime
-
1985
- 1985-12-20 CA CA000498384A patent/CA1281411C/en not_active Expired - Lifetime
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|---|---|
| US4641179A (en) | 1987-02-03 |
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